JP2017166232A - Shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shovel that accurately derives the amount of work by an attachment even in various types of customer sites.SOLUTION: A shovel 50 includes: an undercarriage 1; a revolving super structure 3 mounted on the undercarriage 1; an attachment attached to the revolving super structure 3; a distortion sensor S4 attached to the attachment; posture sensors S1 to S3 for detecting the attachment's posture; and a controller 30 that derives weight of an object lifted up by the attachment on the basis of the attachment's distortion detected by the distortion sensor S4 and the attachment's posture detected by the posture sensors S1 to S3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an excavator provided with an attachment.

  2. Description of the Related Art A work amount monitoring device for a hydraulic excavator that performs an operation of loading an object on a dump truck is known (see Patent Document 1). This work amount monitoring device is a bucket containing a boom, an arm, and earth and sand based on the pressure of hydraulic oil on the bottom side of the boom cylinder (boom bottom pressure) and the pressure of hydraulic oil on the rod side (boom rod pressure). Deriving the power to support the drilling attachment consisting of. A moment around the boom support pin of the excavation attachment is derived based on the boom angle, the arm angle, and the bucket angle and the respective weights of the boom, arm, and empty bucket. Then, the weight of the earth and sand in the bucket is derived from the balance between the supporting force and the moment around the boom support pin.

JP 2002-285589 A

  However, since the above-described work amount monitoring device derives a force that supports the excavation attachment based on the boom bottom pressure and the boom rod pressure, when the bucket moves up and down and does not move horizontally stably, the pressure detection value includes a surge pressure or the like. May occur, and the weight of the earth and sand in the bucket may not be derived with high accuracy. When a skilled operator performs excavation and loading operations, the boom is raised and lowered during turning, and this point cannot be ignored.

  In view of the above, it is desirable to provide an excavator that can derive the amount of work by attachment with higher accuracy even at various customer sites.

  An excavator according to an embodiment of the present invention includes a lower traveling body, an upper swing body mounted on the lower traveling body, an attachment attached to the upper swing body, a strain sensor attached to the attachment, and an attachment of the attachment. A posture sensor that detects a posture; and a control device that derives the weight of an object lifted by the attachment based on the distortion of the attachment detected by the strain sensor and the posture of the attachment detected by the posture sensor. Have.

  By the above-described means, an excavator for deriving the work amount by the attachment with higher accuracy even at various customer sites is provided.

It is a side view of the shovel which concerns on the Example of this invention. It is a figure which shows the structural example of the drive system mounted in the shovel of FIG. It is a figure explaining excavation and loading operation. It is a figure which shows the structural example of a controller. It is a flowchart which shows the flow of a weight derivation process. It is a figure which shows arrangement | positioning of the distortion sensor attached to the boom. It is a figure which shows arrangement | positioning of the distortion sensor attached to the boom. It is a flowchart which shows another flow of a weight derivation process. It is a figure explaining the torsional load which acts on a digging attachment. It is the schematic of the communication network to which the shovel of FIG. 1 is connected.

  First, an excavator 50 as a construction machine according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a side view of the shovel according to the present embodiment. The upper swing body 3 is mounted on the lower traveling body 1 of the excavator 50 via the swing mechanism 2. A boom 4 is attached to the upper swing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 as an end attachment is attached to the tip of the arm 5.

  The boom 4, the arm 5, and the bucket 6 as work elements constituting an excavation attachment that is an example of the attachment are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively.

  A boom angle sensor S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a bucket angle sensor S3 is attached to the bucket 6. The boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 are collectively referred to as “attitude sensors”.

  The boom angle sensor S1 detects the rotation angle of the boom 4. The boom angle sensor S1 is, for example, an acceleration sensor that detects the rotation angle of the boom 4 with respect to the upper swing body 3 by detecting the inclination of the boom 4 with respect to the horizontal plane.

  The arm angle sensor S2 detects the rotation angle of the arm 5. The arm angle sensor S2 is, for example, an acceleration sensor that detects the rotation angle of the arm 5 relative to the boom 4 by detecting the inclination of the arm 5 with respect to the horizontal plane.

  The bucket angle sensor S3 detects the rotation angle of the bucket 6. The bucket angle sensor S3 is an acceleration sensor that detects the rotation angle of the bucket 6 with respect to the arm 5 by detecting the inclination of the bucket 6 with respect to the horizontal plane, for example. The boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 are a potentiometer using a variable resistor, a stroke sensor that detects a stroke amount of a corresponding hydraulic cylinder, and a rotary encoder that detects a rotation angle around a connecting pin. Etc.

  The distortion sensor S4 detects the distortion of the attachment. In this embodiment, the strain sensor S4 is a uniaxial strain gauge that is attached to the surface of the boom 4 and detects strain due to expansion or compression of the boom 4. However, the strain sensor S4 may be a triaxial strain gauge, may be a plurality of uniaxial strain gauges attached to a plurality of locations of the attachment, may be a plurality of triaxial strain gauges, or may be 1 or A combination of a plurality of uniaxial strain gauges and one or a plurality of triaxial strain gauges may be used.

  The upper swing body 3 is provided with a cabin 10, and a power source such as an engine 11 and a vehicle body tilt sensor S5 are mounted thereon. A controller 30, an input device D 1, a sound output device D 2, a display device D 3, a storage device D 4, and an engine controller D 6 are provided in the cabin 10, and a communication device D 5 is provided outside the cabin 10.

  The vehicle body inclination sensor S5 detects the inclination angle of the vehicle body of the excavator 50. In the present embodiment, the vehicle body inclination sensor S5 is an acceleration sensor that detects the inclination angle of the vehicle body with respect to the horizontal plane. The inclination angle of the vehicle body may be derived from, for example, the output of a strain gauge attached to the upper, lower, left, and right surfaces of the boom 4. In this case, the vehicle body tilt sensor S5 may be omitted.

  The controller 30 is a control device that functions as a main control unit that performs drive control of the excavator 50. The controller 30 includes an arithmetic processing unit that includes a CPU and an internal memory. Various functions of the controller 30 are realized by the CPU executing programs stored in the internal memory.

  The input device D1 is a device for the operator of the excavator 50 to input various information to the controller 30. The input device D1 includes, for example, a membrane switch provided on the surface of the display device D3. Further, the input device D1 may be a touch panel or the like.

  The audio output device D <b> 2 outputs various audio information in response to commands from the controller 30. The audio output device D2 is, for example, an in-vehicle speaker connected to the controller 30. The audio output device D2 may be an alarm device such as a buzzer.

  The display device D3 displays a screen including various types of information in response to a command from the controller 30. The display device D3 is an on-vehicle liquid crystal display connected to the controller 30, for example.

  The storage device D4 is a device for storing various information. The storage device D4 is a non-volatile storage medium such as a semiconductor memory, for example. In this embodiment, the storage device D4 stores detection values of the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the distortion sensor S4, the vehicle body tilt sensor S5, and the like, the output value of the controller 30, and the like.

  The communication device D5 is a device that controls wireless communication between the controller 30 and a device outside the excavator 50.

  The engine controller D6 is a device that controls the engine 11. In the present embodiment, the engine controller D6 executes isochronous control for maintaining the engine 11 at a predetermined engine speed by controlling the fuel injection amount and the like.

  FIG. 2 is a diagram illustrating a configuration example of a drive system mounted on the excavator 50, and a mechanical drive system, a high-pressure hydraulic line, a pilot line, and an electric control system are indicated by a double line, a solid line, a broken line, and a dotted line, respectively. .

  The drive system of the excavator 50 mainly includes an engine 11, main pumps 14 </ b> L and 14 </ b> R, a pilot pump 15, a control valve 17, an operation device 26, a pressure sensor 29, and a controller 30.

  The engine 11 is, for example, a diesel engine that operates so as to maintain a predetermined rotational speed. The output shaft of the engine 11 is connected to the input shafts of the main pumps 14L and 14R and the pilot pump 15.

  The main pumps 14L and 14R are devices for supplying hydraulic oil to the control valve 17 via a high pressure hydraulic line, and are, for example, swash plate type variable displacement hydraulic pumps.

  The pilot pump 15 is a device for supplying hydraulic oil to various hydraulic control devices including the operation device 26 via the pilot line 25, and is, for example, a fixed displacement hydraulic pump.

  The control valve 17 is a hydraulic control device that controls the hydraulic system in the excavator 50. Specifically, the control valve 17 includes flow control valves 171 to 176 that control the flow of hydraulic oil discharged from the main pumps 14L and 14R. The control valve 17 is connected to the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, the left traveling hydraulic motor 1A, the right traveling hydraulic motor 1B, and the turning hydraulic motor 2A through the flow control valves 171-176. The hydraulic oil discharged from the main pumps 14L and 14R is selectively supplied to one or a plurality of ones. Hereinafter, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, the left traveling hydraulic motor 1A, the right traveling hydraulic motor 1B, and the turning hydraulic motor 2A are collectively referred to as “hydraulic actuators”.

  The operating device 26 is a device used by an operator for operating the hydraulic actuator. In this embodiment, the operating device 26 supplies the hydraulic oil discharged from the pilot pump 15 to the pilot ports of the flow control valves corresponding to the hydraulic actuators via the pilot line 25. The hydraulic oil pressure (pilot pressure) supplied to each pilot port is a pressure corresponding to the operating direction and operating amount of the lever or pedal of the operating device 26 corresponding to each hydraulic actuator.

  The pressure sensor 29 is an example of an operation content detection unit for detecting the operation content of the operator using the operation device 26. In this embodiment, the pressure sensor 29 detects the operation direction and operation amount of the lever or pedal of the operation device 26 corresponding to each of the hydraulic actuators in the form of pressure, and outputs the detected value to the controller 30. The operation content of the operation device 26 may be derived using the output of a sensor other than the pressure sensor such as a potentiometer.

  The center bypass conduit 40L is a high-pressure hydraulic line that passes through the flow control valves 171, 173, and 175 disposed in the control valve 17. The center bypass conduit 40R is a flow control valve disposed in the control valve 17. High pressure hydraulic lines through 172, 174 and 176.

  The flow rate control valve 171 is a spool valve that controls the flow rate and the flow direction of the hydraulic oil between the main pump 14L, the left-side traveling hydraulic motor 1A, and the hydraulic oil tank. The flow rate control valve 172 is a spool valve that controls the flow rate and flow direction of hydraulic fluid between the main pump 14R, the right-side traveling hydraulic motor 1B, and the hydraulic fluid tank. The flow rate control valve 173 is a spool valve that controls the flow rate and the flow direction of the hydraulic oil between the main pump 14L, the turning hydraulic motor 2A, and the hydraulic oil tank.

  The flow rate control valve 174 is a spool valve that controls the flow rate and the flow direction of the hydraulic oil among the main pump 14R, the bucket cylinder 9, and the hydraulic oil tank. The flow rate control valve 175 is a spool valve that controls the flow rate and flow direction of hydraulic fluid among the main pump 14L, the arm cylinder 8, and the hydraulic oil tank. The flow rate control valve 176 is a spool valve that controls the flow rate and flow direction of hydraulic oil between the main pump 14R, the boom cylinder 7, and the hydraulic oil tank.

  Next, an excavation / loading operation as an example of the operation of the excavator 50 will be described with reference to FIG. First, as shown in FIG. 3A, the operator swivels the upper swing body 3 so that the tip of the bucket 6 is at a desired height from the excavation target with the arm 5 and the bucket 6 open, and the bucket 6 is lowered. When turning the upper swing body 3 and lowering the boom 4, the operator visually confirms the position of the bucket 6. In general, the turning of the upper swing body 3 and the lowering of the boom 4 are performed simultaneously. The above operation is referred to as a boom lowering / turning operation, and this operation section is referred to as a boom lowering / turning operation section.

  When the operator determines that the tip of the bucket 6 has reached a desired height, as shown in FIG. 3B, the operator closes the arm 5 until the arm 5 is substantially perpendicular to the ground. As a result, soil having a predetermined depth is excavated and scraped by the bucket 6 until the arm 5 is substantially perpendicular to the ground surface. Next, the operator further closes the arm 5 and the bucket 6 as shown in FIG. 3C, and as shown in FIG. 3D, the bucket 6 is kept until the bucket 6 becomes substantially perpendicular to the arm 5. Close 6 That is, the bucket 6 is closed until the upper edge of the bucket 6 becomes substantially horizontal, and the collected soil is accommodated in the bucket 6. The above operation is called excavation operation, and this operation section is called excavation operation section.

  Next, when the operator determines that the bucket 6 is closed until it is substantially perpendicular to the arm 5, as shown in FIG. 3E, the bottom of the bucket 6 is desired from the ground while the bucket 6 is closed. Raise the boom 4 until the height becomes. This operation is referred to as a boom raising operation, and this operation section is referred to as a boom raising operation section. Following or simultaneously with this operation, the operator turns the upper swing body 3 and turns the bucket 6 to the earth discharging position as indicated by an arrow AR1. This operation including the boom raising operation is referred to as a boom raising turning operation, and this operation section is referred to as a boom raising turning operation section.

  The boom 4 is raised until the bottom of the bucket 6 reaches a desired height. For example, when the soil is dumped to the loading platform of the dump truck, the bucket 6 hits the loading platform unless the bucket 6 is lifted higher than the loading platform height. Because.

  Next, when the operator determines that the boom raising turning operation is completed, the operator opens the arm 5 and the bucket 6 as shown in FIG. 3 (F) and discharges the soil in the bucket 6. This operation is called a dump operation, and this operation section is called a dump operation section. In the dumping operation, only the bucket 6 may be opened and discharged.

  Next, when the operator determines that the dumping operation has been completed, as shown in FIG. 3G, the operator turns the upper swing body 3 as indicated by the arrow AR2, and brings the bucket 6 right above the excavation position. Move. At this time, the boom 4 is lowered simultaneously with the turning to lower the bucket 6 from the excavation target to a desired height. This operation is a part of the boom lowering turning operation described with reference to FIG. The operator lowers the bucket 6 to a desired height as shown in FIG. 3A, and performs the operation after the excavation operation again.

  The operator proceeds with excavation and loading while repeating this cycle with the above-described “boom lowering turning operation”, “excavation operation”, “boom raising turning operation”, and “dump operation” as one cycle.

  Next, various functions provided in the controller 30 will be described with reference to FIG. FIG. 4 is a diagram illustrating a configuration example of the controller 30.

  The controller 30 receives information from the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the distortion sensor S4, the vehicle body tilt sensor S5, the input device D1, the pressure sensor 29, and the like.

  The controller 30 executes various calculations based on the received information and the information stored in the storage device D4, and outputs a control signal to the audio output device D2, the display device D3, the engine controller D6, etc. according to the calculation results. To do. Further, the controller 30 may wirelessly transmit information, calculation results, and the like received via the communication device D5 to the outside.

  The posture deriving unit 301 is a functional element that detects the posture of the attachment. In the present embodiment, the posture deriving unit 301 derives the posture of the excavation attachment based on the output of the posture sensor configured by the boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3.

  The weight deriving unit 302 is a functional element that derives the weight of an object being lifted by the attachment (hereinafter referred to as “lifting weight”). In the present embodiment, the weight deriving unit 302 derives the lifting weight based on the attitude of the excavation attachment detected by the attitude sensor and the distortion of the excavation attachment detected by the strain sensor S4 when a predetermined derivation condition is satisfied. .

  For example, the weight deriving unit 302 derives the lifted weight by referring to the correspondence table using, as input keys, the distortion of the excavation attachment, the attitude of the excavation attachment, the shape of the excavation attachment, the attachment position of the strain gauge, and the like. The correspondence table is a reference table that stores the correspondence relationship between the attitude of the excavation attachment, the distortion of the excavation attachment, and the lifting weight, and is stored in advance in the storage device D4. The correspondence relationship is determined in advance based on FEM analysis or the like. For example, the weight deriving unit 302 selects a combination closest to the combination of the current excavation attachment posture and strain from the correspondence table, and stores the value of the lift weight stored in association with the selected combination as the current lift. Derived as weight. The distortion of a drilling attachment means the distortion in the 1 or several site | part in a drilling attachment.

  Alternatively, the weight deriving unit 302 may derive the lifting weight by substituting the excavation attachment distortion and the excavation attachment posture into a pre-stored calculation formula. The calculation formula is stored in advance in the storage device D4.

  The “predetermined derivation condition” is a condition for determining the timing at which the weight deriving unit 302 derives the weight. For example, “the bucket 6 has floated” (first derivation condition) and “the dump operation has been completed. (Second derivation condition). The reason that the first derivation condition is that the bucket 6 has floated, that is, the bucket 6 has moved away from the ground, is because it can be estimated that earth and sand and other objects are contained in the bucket 6 when the bucket 6 floats. It is. The reason that “the completion of the dumping operation” is set as the second derivation condition is that when the dumping operation is completed, it can be estimated that the inside of the bucket 6 is empty or the earth and sand that can be dropped have been dropped.

  For example, when it is determined that the turning operation has been performed after the excavation operation, the controller 30 determines that the first derivation condition is satisfied. This is because it can be estimated that the bucket 6 is floating in the air when the turning operation is performed. “After excavation operation” is after the operation of FIG. 3D, and the controller 30 determines the state after the excavation operation from the attitude of the excavation attachment and the distortion of the excavation attachment detected by the strain gauges attached to the upper and lower surfaces of the boom 4. It can be determined whether or not. Specifically, the controller 30 determines that the first derivation condition is satisfied when it is determined that the turning operation lever is operated based on the output of the pressure sensor 29 after the excavation operation. The controller 30 may determine whether or not the turning operation has been performed based on the outputs of the two strain gauges attached to the both side surfaces of the boom 4.

  Alternatively, the controller 30 may determine that the first derivation condition is satisfied when it is determined that the boom 4 has risen above a predetermined height. This is because it can be estimated that the bucket 6 is floating in the air when the boom 4 rises above a predetermined height. Specifically, the controller 30 determines that the first derivation condition is satisfied when it is determined that the boom 4 has risen above a predetermined height based on the output of the boom angle sensor S1.

  Alternatively, the controller 30 may determine that the first derivation condition is satisfied when it is determined that the bucket 6 is closed to a predetermined angle. This is because when the bucket 6 is closed to a predetermined angle, it can be estimated that the bucket 6 is floating in the air. Specifically, the controller 30 determines that the first derivation condition is satisfied when it is determined that the bucket 6 is closed to a predetermined angle based on the output of the bucket angle sensor S3.

  For example, when it is determined that the turning operation is performed during the dumping operation, the controller 30 determines that the second derivation condition is satisfied. This is because it can be estimated that the dumping operation is completed when the turning operation is performed. Specifically, the controller 30 determines that the second derivation condition is satisfied when it is determined that the turning operation lever is operated based on the output of the pressure sensor 29 during the dumping operation.

  Alternatively, the controller 30 may determine that the second derivation condition is satisfied when it is determined that the bucket 6 is opened to a predetermined angle after the first derivation condition is satisfied. This is because it can be estimated that the dumping operation is completed when the bucket 6 is opened to a predetermined angle. Specifically, the controller 30 determines that the second derivation condition is satisfied when it is determined that the bucket 6 is opened to a predetermined angle based on the output of the bucket angle sensor S3.

  When the lifting weight is derived, the weight deriving unit 302 may output a control command to at least one of the audio output device D2, the display device D3, the communication device D5, and the engine controller D6 according to the derived result. For example, the weight deriving unit 302 may display information on the lifting weight on the display device D3, and may output the sound through the audio output device D2. Further, the weight deriving unit 302 may wirelessly transmit information regarding the lifting weight to the outside via the communication device D5. Further, when the lifting weight is equal to or greater than a predetermined value, the output of the engine 11 may be increased via the engine controller D6.

  The posture deriving unit 301 and the weight deriving unit 302 may be realized by an external control device outside the shovel. The external control device is an arithmetic processing device including a CPU and an internal memory, like the controller 30. In this case, the controller 30 wirelessly transmits the acquired information to the external control device through the communication device D5.

  Next, a process in which the controller 30 derives the lifting weight (hereinafter referred to as “weight derivation process”) will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of the weight derivation process. The controller 30 repeatedly executes this weight derivation process at a predetermined control cycle.

  First, the weight deriving unit 302 of the controller 30 determines whether or not the bucket 6 has floated (step ST1). In the present embodiment, the weight deriving unit 302 determines that the bucket 6 has floated when a turning operation is performed after the excavation operation. The weight deriving unit 302 may determine whether or not the bucket 6 has floated based on the pressure of the hydraulic oil in the hydraulic cylinder. In addition, the weight deriving unit 302 determines whether or not the bucket 6 has floated after a predetermined time (for example, 2 seconds) has elapsed since the boom operation lever was operated in the raising direction and before the turning operation lever is operated. May be. This is because when the turning starts, distortion due to the turning inertia force acts as noise.

  When it is determined that the bucket 6 has not floated (NO in step ST1), the weight deriving unit 302 repeats the determination of whether or not the bucket 6 has floated until it is determined that the bucket 6 has floated.

  When it is determined that the bucket 6 has floated (YES in step ST1), the weight deriving unit 302 acquires the posture of the excavation attachment and the distortion of the boom 4 (step ST2). In the present embodiment, the weight deriving unit 302 acquires the posture of the excavation attachment derived by the posture deriving unit 301 based on the output of the posture sensor. Moreover, the distortion of the boom 4 is acquired based on the output of the distortion sensor S4.

  Thereafter, the weight deriving unit 302 derives the lifting weight (step ST3). In the present embodiment, the weight of the earth and sand taken into the bucket 6 is derived as the lifting weight by referring to the correspondence table stored in the storage device D4 using the attitude of the excavation attachment and the distortion of the boom 4 as input keys. .

  With this configuration, for example, the controller 30 can derive the loading weight (= lifting weight) of earth and sand loaded on the dump truck for each cycle of excavation and loading. Further, by accumulating the loading weight for each cycle for each dump truck, the total loading weight of the earth and sand loaded on one dump truck can be derived as a work amount. Further, the controller 30 can derive the excavation weight per predetermined time as the work amount by accumulating the lifting weight for each cycle over a predetermined time. Therefore, the controller 30 can derive the work amount by the excavation attachment with higher accuracy.

  In the present embodiment, the controller 30 derives the lifting weight based on the attitude of the excavation attachment and the output of the strain sensor S4 when it is determined that the bucket 6 has floated. However, the controller 30 may derive the lifting weight based on the attitude of the excavation attachment and the output of the strain sensor S4 at a plurality of time points after determining that the bucket 6 has floated during one cycle. In this case, the controller 30 uses a plurality of lifted weight statistical values (average value, maximum value, minimum value, intermediate value, etc.) derived at a plurality of time points after determining that the bucket 6 is lifted as a final lifted weight. May be output as

  Further, the controller 30 may continuously derive the lifting weight while continuously acquiring the attitude of the excavation attachment and the distortion of the boom 4 regardless of whether or not the bucket 6 has floated. Also in this case, the controller 30 outputs the lifted weight at the time when it is determined that the bucket 6 is lifted or the statistical value of the lifted weight at a plurality of times after it is determined that the bucket 6 is lifted as the final lifted weight. Also good.

  Further, the controller 30 may determine work contents such as excavation work, slope forming work, and floor digging work based on a change in the posture of the excavation attachment. In this case, the controller 30 may associate the identified work content with the work amount derived thereafter and derive the work amount for each work content.

  Next, with reference to FIG.6 and FIG.7, the attachment position of distortion sensor S4 in the boom 4 is demonstrated. 6 and 7 are both perspective views of the boom 4 and show the arrangement of the strain sensors attached to the boom 4.

  In the embodiment shown in FIG. 6, the strain gauge S40 as the strain sensor S4 is formed between the boom cylinder boss 4a and the boom foot 4b so as to detect the distortion of the boom 4 in the longitudinal direction of the boom 4 (the longitudinal direction of the excavation attachment). It is attached to the surface on the back side (+ Z side) of the boom 4. Specifically, the strain gauge S <b> 40 is attached to the central portion of the back surface of the boom 4. In other words, the boom 4 is arranged so as to cross the vertical center plane (the plane including the line segment indicated by the alternate long and short dash line and cutting the boom 4 vertically). However, the strain gauge S40 may be attached to the surface on the ventral side (-Z side) of the boom 4, and is provided on the surface on the back side or the ventral side of the boom 4 between the boom cylinder boss 4a and the boom top 4c. It may be attached. Moreover, you may attach to parts other than a center part. Even when the strain sensor S4 is attached to the back surface or the abdominal surface, the strain sensor S4 is attached so that the tensile compressive stress in the longitudinal direction of the boom 4 can be calculated.

  With this arrangement, the strain sensor S4 can detect, for example, strain due to expansion and contraction of the metal plate on the back side and the belly side of the boom 4 when lifting earth and sand or the like with the excavation attachment. Further, it is possible to detect a strain due to a tensile compression stress caused by a lifting load acting on the excavation attachment (boom 4). Further, the strain sensor S4 may be affixed not to the surface of the boom 4 but inside the back side or the abdomen side. This configuration can prevent damage to the strain sensor S4 even in excavating machines such as excavators.

  In the embodiment shown in FIG. 7, the strain sensor S4 is composed of eight strain gauges S41 to S48. The broken line in FIG. 7 represents a hidden line. The strain gauge S41 and the strain gauge S42 are triaxial strain gauges. The strain gauges S43 to S48 are uniaxial strain gauges. The strain gauges S41 to S44 are provided between the boom cylinder boss 4a and the boom foot 4b on the back side (+ Z side), ventral side (-Z side), left side (-Y side), and right side (+ Y side) of the boom 4. Is attached. The strain gauges S45 to S48 are arranged between the boom cylinder boss 4a and the boom top 4c on the back side (+ Z side), the ventral side (-Z side), the left side (-Y side), and the right side (+ Y side) of the boom 4. Attached to the surface. The strain gauges S41, S42, S45, and S46 are arranged so as to cross the longitudinal center plane of the boom 4. The strain gauges S43, S44, S47, and S48 are attached to the central portion of the left or right surface of the boom 4 so that the tensile and compressive stress in the longitudinal direction of the boom 4 can be calculated. In other words, the boom 4 is disposed so as to cross the horizontal center plane (the plane including the line segment indicated by the two-dot chain line and crossing the boom 4). Further, the strain gauges S41 to S44 are arranged so as to cross the rear reference section R1 as a virtual plane indicated by a one-dot chain line, and the strain gauges S45 to S48 are crossed on the front reference section R2 as a virtual plane indicated by the one-dot chain line. Is arranged. The rear reference cross section R1 and the front reference cross section R2 are perpendicular to the line segment represented by the one-dot chain line in FIG. 6 and the line segment represented by the two-dot chain line in FIG.

  In the embodiment of FIG. 7, all eight strain gauges are attached to the surface of the boom 4, but the number of strain gauges may be less than eight or more than nine. It may be attached to a position. For example, all strain gauges may be attached to the surface of the arm 5. Moreover, it may be distributed and attached to the surface of the boom 4 and the surface of the arm 5. Further, the strain gauge may be attached to the inside of the working element instead of the surface of the working element such as the boom 4 and the arm 5.

  Since the embodiment of FIG. 7 uses eight strain gauges S41 to S48, the strain state of the excavation attachment can be detected with higher accuracy than the embodiment of FIG. 6 using one strain gauge. Therefore, even when the excavation attachment is operating, the distortion state of the excavation attachment can be detected with high accuracy.

  Next, another example of the weight derivation process will be described with reference to FIG. FIG. 8 is a flowchart showing another flow of the weight deriving process. The controller 30 repeatedly executes this weight derivation process at a predetermined control cycle.

  First, the weight deriving unit 302 of the controller 30 determines whether or not the bucket 6 has floated (step ST1). In the present embodiment, the weight deriving unit 302 determines that the bucket 6 has floated when a turning operation is performed after the excavation operation.

  When it is determined that the bucket 6 has not floated (NO in step ST1), the weight deriving unit 302 repeats the determination of whether or not the bucket 6 has floated until it is determined that the bucket 6 has floated.

  When it is determined that the bucket 6 has floated (YES in step ST1), the weight deriving unit 302 acquires the posture of the excavation attachment and the distortion of the boom 4 (step ST2). In the present embodiment, the weight deriving unit 302 acquires the posture of the excavation attachment derived by the posture deriving unit 301 based on the output of the posture sensor. Moreover, the distortion of the boom 4 is acquired based on the output of the distortion sensor S4.

  Thereafter, the weight deriving unit 302 derives the lifting weight (weight before dumping) (step ST3). In this embodiment, by referring to the correspondence table stored in the storage device D4 using the posture of the excavation attachment and the distortion of the boom 4 as input keys, the weight of the earth and sand taken into the bucket 6 is raised (dump) Derived as previous weight).

  Thereafter, the weight deriving unit 302 determines whether or not the dumping operation is completed (step ST4). In the present embodiment, the weight deriving unit 302 determines that the dumping operation is completed when a turning operation is performed during the dumping operation. The weight deriving unit 302 may determine whether or not the dumping operation has been completed based on the hydraulic oil pressure in the hydraulic cylinder, the output of the attitude sensor, and the like. Further, the weight deriving unit 302 may detect the start of the dumping operation when it is determined that the excavation attachment faces the direction of the dump truck based on the image captured by the camera mounted on the shovel. Further, the start of the dumping operation may be detected when it is determined that the bucket 6 is located immediately above the dump truck based on the image. Then, when it is determined that the bucket operating lever is operated in the opening direction based on the output of the pressure sensor 29, or when it is determined that the bucket 6 is opened based on the output of the bucket angle sensor, the dumping operation is completed. You may determine that you did.

  When it is determined that the dump operation has not been completed (NO in step ST4), the weight deriving unit 302 repeats the determination of whether or not the dump operation has been completed until it is determined that the dump operation has been completed.

  When it is determined that the dumping operation is completed (YES in step ST4), the weight deriving unit 302 acquires the posture of the excavation attachment and the distortion of the boom 4 (step ST5). In the present embodiment, the weight deriving unit 302 acquires the posture of the excavation attachment derived by the posture deriving unit 301 based on the output of the posture sensor. Moreover, the distortion of the boom 4 is acquired based on the output of the distortion sensor S4.

  Thereafter, the weight deriving unit 302 derives the lifting weight (weight after dumping) (step ST6). In the present embodiment, the weight of earth and sand remaining in the bucket 6 after the dumping operation is lifted by referring to the correspondence table stored in the storage device D4 using the attitude of the excavation attachment and the distortion of the boom 4 as input keys. Derived as weight (weight after dumping).

  Thereafter, the weight deriving unit 302 calculates the difference between the weight before dumping and the weight after dumping (step ST7). And the weight derivation | leading-out part 302 makes the difference the loading weight, such as earth and sand loaded in the dump truck.

  With this configuration, for example, the controller 30 can derive the loading weight of earth and sand loaded on the dump truck for each cycle of excavation and loading. Moreover, the total weight of the earth and sand loaded on the dump truck can be derived by accumulating the loaded weight for each cycle. Moreover, since the difference between the weight before dumping and the weight after dumping is used as the loading weight, it is possible to prevent the loading weight from including the weight of earth and sand stuck inside the bucket 6 when the dumping operation is completed, for example. .

  Next, the torsional load acting on the excavation attachment will be described with reference to FIG. FIG. 9 is a front view of the excavation attachment of the shovel 50 inclined by an angle θ with respect to the vertical axis. An arrow G <b> 1 pointing vertically downward indicates gravity acting on the center of gravity of the bucket 6 and earth and sand taken into the bucket 6. An arrow G1a pointing in the width direction of the bucket 6 indicates a lateral force that is a component in the width direction of the gravity.

  Due to the presence of the lateral force, when the vehicle body of the excavator 50 is inclined, the arm 5 tries to rotate around the connecting portion between the arm 5 and the boom 4 and generates a torsional load T1 acting on the boom 4. .

  In the embodiment shown in FIG. 9, the strain gauge S <b> 40 as the strain sensor S <b> 4 is a triaxial strain gauge and is attached to the inside of the boom 4. By using the triaxial strain gauge, the controller 30 can detect strains in all directions of the X axis direction, the Y axis direction, and the Z axis direction. Therefore, the controller 30 can calculate not only the bending stress based on the excavation load generated in each direction, but also the shear stress based on the torsional load generated during the eccentric excavation with a sensor attached to one place. Further, a strain gauge may be attached to each direction (X-axis direction, Y-axis direction, Z-axis direction) on the boom 4 as shown in FIG. 7 without using a triaxial strain gauge. .

  The torsional load T1 results in a specific pattern formed by the output of the strain gauge S40. The controller 30 can detect that the torsional load T1 is generated by detecting this specific pattern. Thereby, the component life can be calculated with high accuracy.

  A triaxial strain gauge may be attached to the surface of the arm 5. In this case, since the controller 30 can calculate the shear stress due to the torsional load acting on the arm 5, the life of the arm 5 can be calculated with high accuracy.

  Next, the communication network 100 to which the excavator 50 is connected will be described with reference to FIG. FIG. 10 is a schematic diagram showing a communication network 100 to which the excavator 50 is connected. The communication network 100 mainly includes an excavator 50, a base station 21, a server 22, and a communication terminal 23. The communication terminal 23 includes a mobile communication terminal 23a, a fixed communication terminal 23b, and the like. The base station 21, the server 22, and the communication terminal 23 can be connected to each other using a communication protocol such as the Internet protocol. In addition, each of the shovel 50, the base station 21, the server 22, and the communication terminal 23 may be one or plural. The mobile communication terminal 23a includes a notebook computer, a mobile phone, a smartphone, and the like.

  The base station 21 is a fixed facility that receives information wirelessly transmitted by the excavator 50. For example, the base station 21 transmits and receives information to and from the excavator 50 through satellite communication, mobile phone communication, narrow area wireless communication, and the like.

  The server 22 is a device that stores and manages information wirelessly transmitted by the excavator 50. For example, the server 22 is a computer including a CPU, a ROM, a RAM, an input / output interface, and the like. Specifically, the server 22 acquires and stores information received by the base station 21 through the communication network 100, and manages the information so that an operator (administrator) can refer to the stored information as necessary.

  Further, the server 22 performs various settings of the excavator 50 through the communication network 100. Specifically, the server 22 wirelessly transmits values related to various settings of the excavator 50 to the excavator 50 and changes values related to various settings stored in the controller 30 of the excavator 50.

  Further, the server 22 transmits various information to the communication terminal 23 through the communication network 100. Specifically, the server 22 transmits information on the excavator 50 to the communication terminal 23 when a predetermined condition is satisfied or in response to a request from the communication terminal 23, and the information on the excavator 50 is transmitted. This is communicated to the operator of the communication terminal 23.

  The communication terminal 23 is a device that can refer to information stored in the server 22, and is, for example, a computer that includes a CPU, ROM, RAM, input / output interface, input device, display, speaker, and the like. Specifically, the communication terminal 23 is connected to the server 22 through the communication network 100 so that an operator (administrator) can view information on the excavator 50. Alternatively, the communication terminal 23 receives information regarding the excavator 50 transmitted by the server 22 and allows the operator (administrator) to browse the received information.

  In this embodiment, the server 22 manages information related to the work amount of the excavator 50 wirelessly transmitted by the excavator 50. Therefore, the operator (administrator) can receive and browse information regarding the work amount of the excavator 50 through the communication terminal 23 at an arbitrary timing.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  DESCRIPTION OF SYMBOLS 1 ... Lower traveling body 1A ... Left-side traveling hydraulic motor 1B ... Right-side traveling hydraulic motor 2 ... Turning mechanism 2A ... Turning hydraulic motor 3 ... Upper turning body 4 ... Boom 4a ... Boom cylinder boss 4b ... Boom foot 4c ... Boom top 5 ... Arm 6 ... Bucket 7 ... Boom cylinder 8 ... Arm cylinder 9 ... Bucket cylinder 10. -Cabin 11 ... Engine 14L, 14R ... Main pump 15 ... Pilot pump 17 ... Control valve 21 ... Base station 22 ... Server 23 ... Communication terminal 23a ... Mobile communication Terminal 23b ... Fixed communication terminal 25 ... Pilot line 26 ... Operating device 29 ... Pressure sensor 30 ... Controller 40L, 40R: Center bypass conduit 50 ... Excavator 100 ... Communication network 171-176 ... Flow control valve 301 ... Attitude deriving unit 302 ... Weight deriving unit D1 ... Input device D2 ... Audio output device D3 ... Display device D4 ... Storage device D5 ... Communication device D6 ... Engine controller S1 ... Boom angle sensor S2 ... Arm angle sensor S3 ... Bucket Angle sensor S4 ... Strain sensor S5 ... Body tilt sensor S40-S48 ... Strain gauge

Claims (7)

A lower traveling body,
An upper swing body mounted on the lower traveling body;
An attachment attached to the upper swing body;
A strain sensor attached to the attachment;
An attitude sensor for detecting the attitude of the attachment;
A control device for deriving the weight of an object lifted by the attachment based on the distortion of the attachment detected by the strain sensor and the posture of the attachment detected by the posture sensor;
Excavator. The control device derives the weight of an object lifted by the attachment from the distortion of the attachment detected by the strain sensor when the boom constituting the attachment is raised.
The excavator according to claim 1. The control device derives the weight of the object lifted by the attachment for each cycle of excavation and loading, and accumulates the weight for each cycle to calculate the total load weight of the earth and sand loaded on one dump truck. derive,
The shovel according to claim 1 or 2. The strain sensor includes a strain gauge attached to a central portion of the dorsal surface of the attachment.
The excavator according to any one of claims 1 to 3. The strain sensor includes a triaxial strain gauge,
The excavator according to any one of claims 1 to 4. The strain sensor includes a strain gauge attached between a boom cylinder boss and a boom foot with respect to a boom constituting the attachment.
The excavator according to any one of claims 1 to 5. Calculating a shear stress caused by a torsional load using the detected value of the triaxial strain gauge;
The excavator according to claim 5.

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